5,904 research outputs found
Chemical abundances and ages of the bulge stars in APOGEE high-velocity peaks
A cold high-velocity (HV, 200 km/s) peak was first reported in several
Galactic bulge fields based on the APOGEE commissioning observations. Both the
existence and the nature of the high-velocity peak are still under debate. Here
we revisit this feature with the latest APOGEE DR13 data. We find that most of
the low latitude bulge fields display a skewed Gaussian distribution with a HV
shoulder. However, only 3 out of 53 fields show distinct high-velocity peaks
around 200 km/s. The velocity distribution can be well described by
Gauss-Hermite polynomials, except the three fields showing clear HV peaks. We
find that the correlation between the skewness parameter () and the mean
velocity (), instead of a distinctive HV peak, is a strong indicator
of the bar. It was recently suggested that the HV peak is composed of
preferentially young stars. We choose three fields showing clear HV peaks to
test this hypothesis using the metallicity, [/M] and [C/N] as age
proxies. We find that both young and old stars show HV features. The similarity
between the chemical abundances of stars in the HV peaks and the main component
indicates that they are not systematically different in terms of chemical
abundance or age. In contrast, there are clear differences in chemical space
between stars in the Sagittarius dwarf and the bulge stars. The strong HV peaks
off-plane are still to be explained properly, and could be different in nature.Comment: 13 pages, 10 figures, published in ApJ. Updated to match the final
ApJ published version. Minor revisions to the text and Figure
Torus knots and mirror symmetry
We propose a spectral curve describing torus knots and links in the B-model.
In particular, the application of the topological recursion to this curve
generates all their colored HOMFLY invariants. The curve is obtained by
exploiting the full Sl(2, Z) symmetry of the spectral curve of the resolved
conifold, and should be regarded as the mirror of the topological D-brane
associated to torus knots in the large N Gopakumar-Vafa duality. Moreover, we
derive the curve as the large N limit of the matrix model computing torus knot
invariants.Comment: 30 pages + appendix, 3 figure
Dry eye disease in mice activates adaptive corneal epithelial regeneration distinct from constitutive renewal in homeostasis
Many epithelial compartments undergo constitutive renewal in homeostasis but activate unique regenerative responses following injury. The clear corneal epithelium is crucial for vision and is renewed from limbal stem cells (LSCs). Using single-cell RNA sequencing, we profiled the mouse corneal epithelium in homeostasis, aging, diabetes, and dry eye disease (DED), where tear deficiency predisposes the cornea to recurrent injury. In homeostasis, we capture the transcriptional states that accomplish continuous tissue turnover. We leverage our dataset to identify candidate genes and gene networks that characterize key stages across homeostatic renewal, including markers for LSCs. In aging and diabetes, there were only mild changes with \u3c15 dysregulated genes. The constitutive cell types that accomplish homeostatic renewal were conserved in DED but were associated with activation of cell states that comprise adaptive regeneration. We provide global markers that distinguish cell types in homeostatic renewal vs. adaptive regeneration and markers that specifically define DED-elicited proliferating and differentiating cell types. We validate that expression of SPARC, a marker of adaptive regeneration, is also induced in corneal epithelial wound healing and accelerates wound closure in a corneal epithelial cell scratch assay. Finally, we propose a classification system for LSC markers based on their expression fidelity in homeostasis and disease. This transcriptional dissection uncovers the dramatically altered transcriptional landscape of the corneal epithelium in DED, providing a framework and atlas for future study of these ocular surface stem cells in health and disease
Integrated approach to designing growth factor delivery systems
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154661/1/fsb2fj067873com-sup-0001.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154661/2/fsb2fj067873com.pd
New improved Moser-Trudinger inequalities and singular Liouville equations on compact surfaces
We consider a singular Liouville equation on a compact surface, arising from
the study of Chern-Simons vortices in a self dual regime. Using new improved
versions of the Moser-Trudinger inequalities (whose main feature is to be
scaling invariant) and a variational scheme, we prove new existence results.Comment: to appear in GAF
Activation of the innate immune receptor Dectin-1 upon formation of a 'phagocytic synapse'.
Innate immune cells must be able to distinguish between direct binding to microbes and detection of components shed from the surface of microbes located at a distance. Dectin-1 (also known as CLEC7A) is a pattern-recognition receptor expressed by myeloid phagocytes (macrophages, dendritic cells and neutrophils) that detects β-glucans in fungal cell walls and triggers direct cellular antimicrobial activity, including phagocytosis and production of reactive oxygen species (ROS). In contrast to inflammatory responses stimulated upon detection of soluble ligands by other pattern-recognition receptors, such as Toll-like receptors (TLRs), these responses are only useful when a cell comes into direct contact with a microbe and must not be spuriously activated by soluble stimuli. In this study we show that, despite its ability to bind both soluble and particulate β-glucan polymers, Dectin-1 signalling is only activated by particulate β-glucans, which cluster the receptor in synapse-like structures from which regulatory tyrosine phosphatases CD45 and CD148 (also known as PTPRC and PTPRJ, respectively) are excluded (Supplementary Fig. 1). The 'phagocytic synapse' now provides a model mechanism by which innate immune receptors can distinguish direct microbial contact from detection of microbes at a distance, thereby initiating direct cellular antimicrobial responses only when they are required
Human RTEL1 associates with Poldip3 to facilitate responses to replication stress and R-loop resolution
International audienc
An improved geometric inequality via vanishing moments, with applications to singular Liouville equations
We consider a class of singular Liouville equations on compact surfaces
motivated by the study of Electroweak and Self-Dual Chern-Simons theories, the
Gaussian curvature prescription with conical singularities and Onsager's
description of turbulence. We analyse the problem of existence variationally,
and show how the angular distribution of the conformal volume near the
singularities may lead to improvements in the Moser-Trudinger inequality, and
in turn to lower bounds on the Euler-Lagrange functional. We then discuss
existence and non-existence results.Comment: some references adde
SARS-CoV-2 infects human engineered heart tissues and models COVID-19 myocarditis
There is ongoing debate as to whether cardiac complications of coronavirus disease-2019 (COVID-19) result from myocardial viral infection or are secondary to systemic inflammation and/or thrombosis. We provide evidence that cardiomyocytes are infected in patients with COVID-19 myocarditis and are susceptible to severe acute respiratory syndrome coronavirus 2. We establish an engineered heart tissue model of COVID-19 myocardial pathology, define mechanisms of viral pathogenesis, and demonstrate that cardiomyocyte severe acute respiratory syndrome coronavirus 2 infection results in contractile deficits, cytokine production, sarcomere disassembly, and cell death. These findings implicate direct infection of cardiomyocytes in the pathogenesis of COVID-19 myocardial pathology and provides a model system to study this emerging disease
Non-extremal Black Hole Microstates: Fuzzballs of Fire or Fuzzballs of Fuzz ?
We construct the first family of microstate geometries of near-extremal black
holes, by placing metastable supertubes inside certain scaling supersymmetric
smooth microstate geometries. These fuzzballs differ from the classical black
hole solution macroscopically at the horizon scale, and for certain probes the
fluctuations between various fuzzballs will be visible as thermal noise far
away from the horizon. We discuss whether these fuzzballs appear to infalling
observers as fuzzballs of fuzz or as fuzzballs of fire. The existence of these
solutions suggests that the singularity of non-extremal black holes is resolved
all the way to the outer horizon and this "backwards in time" singularity
resolution can shed light on the resolution of spacelike cosmological
singularities.Comment: 34 pages, 10 figure
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